This ontology adds vocabulary of units of measurement and quantities and new unit classes to QUDT.
The Allotrope QUDT Extension Ontology (REC/2025/12)
An alternative to qudt:symbol that provides a unique symbol for a given unit within the QUDT and QUDT-EXT namespaces.
An alternative to qudt:symbol that provides a unique symbol for a given unit within the QUDT and QUDT-EXT namespaces. The symbol for a unit is a glyph that is used to represent the unit in a compact form. For example, the symbol for the US Dollar is $.
The UCUM case insensitive symbol for a unit.
Unified Code for Units of Measure case insensitive code
The UCUM case sensitive symbol for a unit.
Unified Code for Units of Measure case sensitive code
The UCUM symbol recommended for use in print.
Unified Code for Units of Measure print symbol
A commonly used abstraction for dimensionless absorbance measurements.
A measure of activity divided by mass of a radioactive material. [Allotrope]
The reciprocal of electrical resistivity, representing a material's ability to conduct electric current.
A fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current.
A measure of the quantity of active enzyme present.
Force Per Area is the amount of force applied per unit area. [Allotrope]
A measure of the ability to increase power or amplitude of a signal.
A measure of the infectivity of a biological agent.
Inverse Molar Concentration Per Time Unit
Inverse Molar Concentration Per Time Unit is the measure of the rate and direction of a chemical reaction. [Allotrope]
Mass per amount of substance is the mass of some material per defined amount of the material. [Allotrope]
The degree of concentration of countable objects.
Number per time is the number of specified objects per unit time. [Allotrope]
Number times time is the number of specified objects multiplied by unit time. [Allotrope]
A measure of the concentration of dissolved particles in solution.
Quantity per time is the amount of some measured quantity divided by unit time. [Allotrope]
Quantity times time is the amount of some measured quantity multiplied by unit time. [Allotrope]
Quantity times volume is the amount of some measured quantity multiplied by unit volume. [Allotrope]
An abstraction for common dimensionless ratios.
An abstraction for dimensionless refractive index measurements.
A commonly used abstraction for dimensionless response rate measurements.
A commonly used abstraction for dimensionless response measurements.
A property of solids defined as the total surface area of a material per unit mass or volume.
Volume concentration is the volume of some material component relative to the total volume of material. [Allotrope]
National Aeronautics and Space Administration
In chemistry, absorbance or decadic absorbance is the common logarithm of the ratio of incident to transmitted radiant power through a material, and spectral absorbance or spectral decadic absorbance is the common logarithm of the ratio of incident to transmitted spectral radiant power through a material.
A correction factor used in chromatography for the compressibility of the mobile phase.
compressibility correction factor (quantity kind)
Count is the number of countable, specified objects.
Electrical conductivity is an intrinsic property that quantifies how strongly a given material opposes the flow of electric current.
Electrical conductivity or specific conductance is the reciprocal of electrical resistivity, and measures a material's ability to conduct an electric current.
Enzyme activity is a measure of the quantity of active enzyme present and is thus dependent on conditions, which should be specified.
Gain is the ratio of output signal strength to input voltage. [Allotrope]
2021-07-01 Changed pref label. [Allotrope]
Number per time is the number of specified objects per unit time.
Number times time is the number of specified objects times unit time
Number times time is the number of specified objects times unit time. [Allotrope]
Quantity per time is a kind of quantity divided by a factor of unit time.
Quantity times time is a kind of quantity multiplied by a factor of unit time.
Quantity times volume is a kind of quantity multiplied by a factor of unit volume.
In optics, the refractive index or index of refraction of a material is a dimensionless number that describes how light propagates through that medium.
Specific surface area (SSA) is a property of solids defined as the total surface area of a material per unit of mass.
A unit for the correction factor used in chromatography for the compressibility of the mobile phase.
2020-08-19 Add UCUM codes, changed symbol. [Allotrope]
The mass unit of avoirdupois pound (1 lbav = 0,45359237 kg). [ISO 11240]
2020-08-19 Add UCUM codes, changed symbol [Allotrope]
This is an SI-derived unit for the quantity of activity content. It is expressed algebraically in terms of other SI units. [ISO 11240]
CFU is an arbitrary unit which is used to count the number of colonies formed by viable microorganisms. It is related to a specific bioassay test method. Note that the number expression “billion”? is replaced by the unambiguous power of 10. The meaning of “billion”? differs between countries. 10^9 “Billion”? is replaced by a power of 10. The notion of “what is counted”? is not a part of the unit, but belongs to the method definition (“count of organisms”? in this case). [ISO 11240]
The unit CCID50 per milliliter expresses the result of quantifying an infectious agent in a cell culture. It is a titre, expressing the highest dilution of the specimen which produces a cytopathic effect in 50 % of the cell cultures or wells inoculated. [ISO 11240]
normalized heat flow rate, normalized by mass in gram
heat flow rate, used for quantifying differential power
Degree times Milliliter per Gram Times Decimeter
A drop is a variable amount of fluid and depends on the device and technique used to produce the drop and on the physical properties of the fluid. This is similar to units like cup, tablespoon and teaspoon that depend on the spoon or cup and are not exact either. However, in clinical medicine, medication is dispensed by drops and, unlike a “tablet”?, a drop refers to a real physical kind-ofquantity, volume, though not very exact (1 drp = 1 ml/12). [ISO 11240]
"Elementary Charge", usually denoted as e, is the electric charge carried by a single proton, or equivalently, the negation (opposite) of the electric charge carried by a single electron. This elementary charge is a fundamental physical constant. To avoid confusion over its sign, e is sometimes called the elementary positive charge. This charge has a measured value of approximately 1.60217662 × 10-19 coulombs.
The enzyme unit (U) is a unit for the amount of a particular enzyme 1 U = µmol/min = 1/60 nkat
Nomenclature Committee of the International Union of Biochemistry (NC-IUB) (1979). "Units of Enzyme Activity". Eur. J. Biochem. 97 (2): 319–20
FFU/mL is used to represent viral infectivity as measured in a sensitive assay in cell culture using immunofocus technology. The titre is determined by visualizing infected areas of a cell monolayer by probing with virus-specific monoclonal antibodies and results recorded as FFU/ml. [ISO 11240]
A unit for the quantity mass concentration. [ISO 11240]
2020-08-19 Add UCUM codes, changed liter symbol. [Allotrope]
2020-09-09 Fix conversionMultiplier. [Allotrope]
2020-06-21 Changed pref label. [Allotrope]
The unit of million cells per milliliter expresses the result of quantifying the amount of cells within a volume.
2023-09-12 Corrected conversion multiplier. [Allotrope]
2020-08-19 Changed UCUM print symbol. [Allotrope]
2020-08-19 Added UCUM codes. [Allotrope]
2020-09-09 Changed unit label to osm. [Allotrope]
A dimensionless unit, it is equivalent to 10−9. [ISO 11240]
A dimensionless unit, it is equivalent to 10−6. [ISO 11240]
A dimensionless unit for peak areas. [Allotrope]
The unit is per minute, regardless of what is being counted. [ISO 11240]
number of pixels per millimeter in a raster image
The NCI-concept 'plaque forming unit equiv 1000 mouse LD50' is mapped to [PFU] for 'plaque forming unit'. The fact that this quantity happens to be equivalent to '1000 mouse LD50' is not considered to be part of the unit concept but a component of the method definition (e.g. a titration end point). [ISO 11240]
The unit of plates per meter expresses the result of quantifying the density of theoretical plates in chromatography.
Relative Fluorescence Unit Times Milliliter
An arbitrary unit representing the response from some detector. [Allotrope]
The number of discrete samples of some thing per second.
An explicit unit to say something has no units.
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